The present invention relates to the preparation of novel aromatic compounds halogenated in the nucleus and containing both ether and ester groups, which are derived from the General Formula I, and to these compounds themselves. ##STR2##
The subject matter of the invention, therefore, is the three isometric o-, m- and p-haloaryloxymethyl (or -mercaptomethyl)benzoic acid halophenyl esters and thiohalophenyl esters of Formula I, wherein X can represent oxgyen or sulfur and the X's can be the same or different.
If the ester group contains sulfur, the compounds of Formula I can also be referred to as substituted thiobenzoic acid-S-aryl esters.
R represents the residue of a mononuclear or polynuclear, halogen-substituted compound, which can include the substituent ##STR3##
The moiety R can be unsubstituted, or it may have substituents, especially halogen, e.g. chlorine and/or bromine atoms. The number of halogen atoms per aromatic ring preferably being from 2 to 5. The R's can be alike or different.
Especially the benzene ring is to be the basis of the nuclear rings, but other aromatic rings and heterocyclic rings are possible.
In the case of noncondensed polynuclear rings, the diphenyl radical is preferred among the nuclei joined by a single bond, while in the case of the rings joined by atom groups, benzene nuclei are preferred, the preferred connecting links being hydrocarbon moieties, such as a methylene group or a dialkylmethylene group, a chalcogen atom, such as an oxygen or sulfur atom, or the group -SO -, and still others are possible.
These polynuclear moieties are thus derived from the general formula ##STR4## wherein the connecting link Y has the meaning given above and R.sub.1 to R.sub.8 represent hydrogen or halogen, the moieties R.sub.1 to R.sub.8 being able to be identical to one another or different.
Additional subject matter of the invention is a method for the preparation of the compounds of Formula I, which is characterized in that o-, m- or p-chloromethylbenzoic acid esters of halogenated phenols and/or thiophenols being monovalent or polyvalent, mononuclear or polynuclear, and alkali salts of unsubstituted or halogen-substituted phenols, or of the thiophenols corresponding thereto, are reacted with one another in appropriate solvents at elevated temperature.
The chlormethylbenzoic acid esters of phenols or thiophenols which are used as starting materials are easily obtainable substances whose preparation is described in German Patent Application P 24 47 385.6. (U.S. Pat. Ser. No. 619,351, filed Oct. 3, 1975, now abandoned and replaced by Ser. No. 804,837, filed June 8, 1977.)
The process is generally performed by placing the isomeric chloromethylbenzoic acid or chlormethylthiobenzoic acid halophenyl ester used as starting solution into a solution or suspension of an alkali salt of a (halo)phenol or (halo)thiophenol in an inert solvent or reaction medium, and bringing this mixture to reaction at elevated temperature, with stirring. The ether-esters of the invention which are thus formed precipitate, as a rule, and are easily isolated, for example by suction filtering the cooled reaction mixture. The sodium chloride formed in the preparation reaction is removed from the ether-esters, and then the reaction product is dried in a conventional manner. The ether-esters of Formula I are obtained by the method of the present invention in a high yield and in good purity.
The alkali phenolates of the First Main Group of the Periodic System can be used as alkali salts of the (halo)phenols, preferably the sodium and/or potassium phenolates.
It is a special feature of the present process that the alkali phenolates are prepared in situ in the solvent from the phenols and the particular alkali hydroxide or from the solutions thereof, which permits an especially economical procedure.
Suitable reaction media for the performance of the reaction of the process of the invention are the solvents or suspension media which are known in ester formation of phenol ether formation processes and are inert in the said processes, such as, for example, hydrocarbons, including xylene, ethers, such as dioxane, sulfoxides, such as dimethylsufoxide, but especially alkyleneglycolmonoalkyl ethers on account of their good dissolving ability with regard to the alkali phenolates to be used in accordance with the invention. Ethyleneglycol monomethyl ether, hereinafter referred to simply as methyl glycol, is used to special advantage in the performance of the process of the invention.
However, even other representatives of this group of solvents can be used with similar good success, such as for example, ethyleneglycol monoethyl ether, ethyleneglycol monobutyl ether, 1,4-butyleneglycol monomethyl ether, 1,4-butyleneglycol monoethyl ether, and others.
The reaction components are subjected to the reaction in equal molar ratios, as a rule, although a slight excess amounting, for example, to 10% by weight of chloromethylbenzoic acid ester, can be used.
One very especially advantageous variant of the present process is to set out, not from the chloromethyl(thio)benzoic acid esters, but from the o-, m- and/or p-chloromethylbenzoyl chloride, which is capable of yielding the new compounds of Formula I directly in a one-vessel process. In this one-vessel reaction procedure, the alkali phenolates can also be formed in situ. In this embodiment the ester is formed in situ and is then reacted to form the ether-ester.
The temperature range in which the process of the present invention can be performed with especial success has been found to be from +10.degree. to 150.degree. C, preferably from 25.degree. to 130.degree. C. In the case of the one-vessel reaction for the preliminary ester formation, a temperature from 10 to about 40.degree. C is desirable.
The new substances of Formula I in accordance with the invention are effective and advantageous fire-retardant agents for plastics, e.g. synthetic plastics, such as, for example, polyolefins or polystyrene, acrylonitrile-butadiene-styrene polymers, polyesters, and numerous others.
Polyolefins, in the meaning of the present invention, are polyethylene of high or low density, polypropylene, polybutylene, polymethylpentene, and others.
The substances of the invention comply to a high degree with the requirements which must be met by a fire-retardant agent, and therefore another subject of this invention consists in the use of the ether-esters of Formula I as fire-retardant agents in plastics, as well as in these fire-retardant plastics themselves.
The ether-esters of the invention can easily be incorporated into plastics; they are well compatible with the polymers, as a rule they do not chalk out, and they are entirely stable at the required fabrication temperatures.
Another advantage of the substances of the invention is that relatively small amounts suffice for the achievment of good fire-retardancy, resulting in only minor alterations of the mechanical and physical properties of the finished products.
Still another advantage is that the halogen content of the substances of Formula I does not need to be as high as it does in many of the conventional fire-retardant agents known heretofore. Surprisingly, ether-esters of the invention having bromine contents of only 40 to 50 wt.-% have a good, and in some cases even equally good or better fire-retardant action as known compounds of higher degrees of bromination. Since the amount of bromine is an important cost factor in fire-retardant agents, comparatively low bromine contents present a technical and economical advantage.
The substances of the present invention are used in the polymers together with synergistic compounds such as zinc borate, sodium antimonite and, to special advantage, antimony trioxide.
In general, the fire-retardant agents of the invention are added in amounts of 2 to 15 wt.-%, preferably 3 to 10 wt.-%. Of the antimony trioxide, from 0.5 to 8 wt.-% is used, and, to special advantage, from 1 to 5 wt-% with respect to the total amount of the plastic.
The incorporation of the fire-retardant additives can be accomplished in a conventional manner by mixing on heated rolls, mix-extruding, or other appropriate method. In addition, the adjuvant additives required in any particular case can be incorporated, such as, for example, lubricants, stabilizers, pigments, or other conventional additives.